Ppm changes very quickly after new resin added

Discussion in 'Water Fed Pole Cleaning' started by SMS cleaning, Mar 26, 2015.

Advertisement
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Welcome to the UK Window Cleaning Forums.
    Starting or own a window cleaning business? We're a network of window cleaners sharing advice, tips & experience. Rounds for sale & more. Join us today!

  1. SMS cleaning

    SMS cleaning Newcomer
    Member

    Joined:
    Mar 1, 2015
    Messages:
    4
    Likes Received:
    0
    Hi need advise running a merlin 3stage purification unit and a sta-rite 618 resin tank which takes approx 7.5litres of resin ,I live in a very hard water area approx 330ppm at start ,I am having huge problems as resin is lasting approx two 500 litre tank fills and is climbing to 5ppm ,I need advise why this a happening if I change resin and comes out at 0 ppm at the start ,I purify the water in my garden first then transfer to vehicle .many thanks Lyndon
     
    Advertisement
  2. Smurf

    Smurf Banned
    Member

    Joined:
    Mar 18, 2012
    Messages:
    20,811
    Likes Received:
    3,812
    Something doesn't sound quite right there for sure as that amount of resin should last longer than 1000 litres.

    Have you checked the ro output ppm before it goes into the resin tank as the membranes/filters maybe on the way out?
    what is your tap tds?
    what is the ro output tds?
    what resin are you using?

    Also are you aware of tds creep as that will kill resin quicker too?
    .
     
  3. spruce

    spruce Grand Master
    Member

    Joined:
    Jun 4, 2012
    Messages:
    2,540
    Likes Received:
    737
    #3 spruce, Mar 26, 2015
    Last edited: Mar 26, 2015
    Lots of questions.

    What is the tds of the pure leaving the r/o and before the di vessel.

    What did you last change the carbon filter?

    How old is the r/o?
     
  4. SMS cleaning

    SMS cleaning Newcomer
    Member

    Joined:
    Mar 1, 2015
    Messages:
    4
    Likes Received:
    0
    Hi leaving ro before hits resin is roughly 36ppm and tap water is roughly 330 ppm the resin is unger ion mixed bed resin from wintecs brand new and is kepted sealed im wondering if water pressure is not high enough ,what filters are in ro i think theres two sediment filters not sure when last changed cheers J
    murf, post: 226484, member: 4889"]Something doesn't sound quite right there for sure as that amount of resin should last longer than 1000 litres.

    Have you checked the ro output ppm before it goes into the resin tank as the membranes/filters maybe on the way out?
    what is your tap tds?
    what is the ro output tds?
    what resin are you using?

    Also are you aware of tds creep as that will kill resin quicker too?
    .[/QUOTE]
    Hi
     
  5. spruce

    spruce Grand Master
    Member

    Joined:
    Jun 4, 2012
    Messages:
    2,540
    Likes Received:
    737
    #5 spruce, Mar 26, 2015
    Last edited: Mar 26, 2015
    Sorry, Smurf got there first.

    Merlins are renowned for high waste and poor efficiency. But your figures don't add up.

    Using a 7 liter di your resin should be purify about 5000 litres at 36ppm. However, taking into consideration tds creep it should last longer than 1000 liters. If you were using your di to purify water at 330ppm, then your resin would only last 1000 liters.

    At 330 ppm in and 36 out, your r/o is working to 89% efficiency - poor from normal r/o standards but with a new Merlin only achieving 90% then its still OK by Merlin (GE) standards.
    Alex Gardiner now sells the superceded Merlin r/o and his rejection rate figures are better with a booster pump. So he recommends a booster pump in most cases from what I can gather.

    However, another cleaner I know of sold his Merlin as it was costing too much with metered water and resin. He now has a 4040 r/o.

    For us our 4040 is working with a 50psi input pressure, no booster and a 50 / 50 pure to waste ratio. Input tds is around 115 to 125 and output after r/o is 2. The di vessel is 6.5 liters and lasts 18 months between changes - even considering tds creep. I couldn't be asked to disconnect the di vessel and run the pure into the IBC tank or to waste for a few moments to save resin.
     
  6. spruce

    spruce Grand Master
    Member

    Joined:
    Jun 4, 2012
    Messages:
    2,540
    Likes Received:
    737
    #6 spruce, Mar 26, 2015
    Last edited: Mar 26, 2015
    A Merlin has 3 housings. The top housing is the carbon block and the remaining 2 are membranes. I recommended to a fellow window cleaner to add a single sediment prefilter before the inlet as our water is laden with sediment. (His r/o is just over 3 years old and his rejection rate is much less than yours.)

    Depending on your usage of water per day, you need to replace that carbon block every 3 months at most. If you are using 300 liters of pure a day and you work 20 days a month, that carbon block has to remove chlorine from 36000 liters of water per month.

    If I was happy with my Merlin, I would remove that carbon block and add 2 x 20" prefilter housings. I would fit a sediment filter in the first housing and a Fiberdyne filter in the second housing. At 36000 liters of water a month, the Fiberdyne c/b will last you 2 months.

    But personally, I would sell your Merlin on Ebay and replace it with a 4040.
    Using 6000 liters of pure a month will cost you £32.00 a month on resin, and the resin will have to be changed every 3 weeks (calculated on a 25 liter bag of resin costing £80.00).

    A 4040 should produce pure at 7ppm which means your resin costs will be £6 per month and you will have to change your resin every 4 months.

    If your are on a meter, water savings would also be expected. With a high tds of 330 I would guess a 4040 pure to waste ratio would need to be around 2 or 3 to 1 (waste to pure). That equates to just over half the water your Merlin will use.

    A Merlin is primarily an undercounter kitchen sink water purifier. It doesn't have to be that efficient for drinking water. But it isn't good enough for window cleaners IMHO.
     
    • Informative Informative x 2
    • List
Advertisement